[Beta-blockers for patients with hypertension].
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Adrenergic beta-Antagonists↗
Biomedical subjects
Takashi Haneda
Publications and source records attributed to Takashi Haneda.
[Calcium channel blocker for protection against hypertensive target-organ damage].
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Calcium Channel Blockers↗
Roles of calcineurin and calcium/calmodulin-dependent protein kinase II in pressure overload-induced cardiac hypertrophy.
Calcineurin and calcium/calmodulin-dependent protein kinase (CaMK) II have been suggested to be the signaling molecules in cardiac hypertrophy. It was not known, however, whether these mechanisms are involved in cardiac hypertrophy induced by pressure overload without the influences of blood-derived humoral factors, such as angiotensin II. To elucidate the roles of calcineurin and CaMK II in this situation, we examined the effects of calcineurin and CaMK II inhibitors on pressure overload-induced expression of c-fos, an immediate-early gene, and protein synthesis using heart perfusion model. The hearts isolated from Sprague-Dawley rats were perfused according to the Langendorff technique, and then subjected to the acute pressure overload by raising the perfusion pressure. The activation of calcineurin was evaluated by its complex formation with calmodulin and by its R-II phosphopeptide dephosphorylation. CaMK II activation was evaluated by its autophosphorylation. Expression of c-fos mRNA and rates of protein synthesis were measured by northern blot analysis and by 14C-phenylalanine incorporation, respectively. Acute pressure overload significantly increased calcineurin activity, CaMK II activity, c-fos expression and protein synthesis. Cyclosporin A and FK506, the calcineurin inhibitors, significantly inhibited the increases in both c-fos expression and protein synthesis. KN62, a CaMK II inhibitor, also significantly prevented the increase in protein synthesis, whereas it failed to affect the expression of c-fos. These results suggest that both calcineurin and CaMK II pathways are critical in the pressure overload-induced acceleration of protein synthesis, and that transcription of c-fos gene is regulated by calcineurin pathway but not by CaMK II pathway.
Animals↗
Contribution of macrophage migration inhibitory factor to extracellular signal-regulated kinase activation by oxidative stress in cardiomyocytes.
In response to oxidative stress, the pathogenesis of a number of cardiovascular events and several genes are stimulated by extracellular signal-regulated kinases (ERK1/2). Biphasic (early, 10 min; and delayed, 120 min) ERK1/2 activation by H(2)O(2), a reactive oxygen species, was observed in cultured neonatal rat cardiomyocytes. We investigated the hypothesis that the delayed activation of ERK1/2 depends on a factor secreted by oxidative stress (FSO). The delayed activation was inhibited by calphostin C, a protein kinase C inhibitor. Conditioned medium (CM) obtained from cells stimulated with H(2)O(2) induced rapid and monophasic ERK1/2 activation, which was not inhibited by calphostin C. In contrast, calphostin C-pretreated CM did not activate ERK1/2. Macrophage migration inhibitory factor (MIF) was one of the candidate FSOs activating ERK1/2. The existence of MIF in CM, the recombinant MIF-stimulated ERK1/2 rapid activation, and anti-MIF neutralizing antibody-induced inhibition of the delayed activation implied that MIF could be the FSO. Pretreatment of cardiomyocytes with a mitogen-activated protein kinase/ERK kinase (MEK) inhibitor did not suppress the MIF secretion, although it prevented the ERK1/2 activation by H(2)O(2). These results indicate that MIF is secreted from cardiomyocytes as a result of oxidative stress and activates ERK1/2 through a MEK1/2-dependent mechanism, although the secretion is not regulated by ERK1/2 but by protein kinase C.
Animals↗
Methylenetetrahydrofolate reductase gene polymorphism, hyperhomocysteinemia, and cardiovascular diseases in chronic hemodialysis patients.
Cardiovascular disease (CVD) is the principle cause of death in patients with end-stage renal disease. Some gene polymorphisms and hyperhomocysteinemia have been implicated in the pathogenesis of CVD. The aim of this study was to assess the relationships between angiotensin-converting enzyme genotype, endothelial nitric oxide synthase genotype, and methylenetetrahydrofolate reductase (MTHFR) genotype and CVD in patients on hemodialysis and to clarify the determinants of plasma homocysteine level. One hundred and sixty-eight patients on hemodialysis (87 males and 81 females, mean age 60.7 +/- 13.1 years) were included. A history of CVD was present in 25% of the patients. There was a significant difference in the distributions of MTHFR non-VV genotype and MTHFR VV genotype between patients with a CVD history and patients without a CVD history, but no difference in the distributions of angiotensin-converting enzyme genotypes and endothelial nitric oxide synthase genotypes. The plasma homocysteine concentration was significantly higher in patients with MTHFR VV genotype than in patients with MTHFR non-VV genotype. The plasma homocysteine concentration was negatively correlated with plasma vitamin B12 concentration and plasma folate concentration. On stepwise multiple-regression analysis for the predictors of plasma homocysteine concentration, MTHFR VV genotype and gender were significant. In conclusion, MTHFR polymorphism may be a risk factor for CVD in patients on hemodialysis, and MTHFR VV genotype and gender may be strong determinants of the plasma homocysteine level.
Adult↗
Cyclical changes in high-energy phosphates during the cardiac cycle by pacing-Gated 31P nuclear magnetic resonance.
Whether cyclical changes in energy-related phosphate metabolites arise during a cardiac cycle in isolated rat hearts and are affected by differences in myosin isozyme composition was determined. Myocardial adenosine triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi), and intracellular pH in normal, hypothyroid and hyperthyroid rat hearts were measured using the pacing-gated 31P nuclear magnetic resonance technique. Maximal decrease in ATP and PCr, and maximal increase in Pi at the peak-systole in normal rat hearts were observed. In hypothyroid and hyperthyroid rats, similar cyclical changes in phosphate metabolites were observed during the cycle. However, the magnitude of fluctuations was smaller in hypothyroid rats and larger in hyperthyroid rats compared with that observed in normal rats. Cardiac myosin isozyme patterns were also different amongst the experimental groups. The results suggest that cyclical changes and the magnitude of fluctuations in energy-related phosphate metabolites during a cardiac cycle may depend on the cardiac workload and the intrinsic properties in the enzyme kinetics of myosin.
Adenosine Triphosphate↗